掌握煤层开采覆岩破坏规律及导水裂隙带演化特征,是对其进行源头减损设计及采后分区差异化地表生态修复的前提。以神东石圪台矿典型工作面为工程背景,采用自主研发的模拟试验平台开展多煤层开采覆岩破坏及其自修复特征研究,并揭示了导水裂隙带高度与工作面宽深比、深厚比的关系,得到了导水裂隙带高度的预测公式。研究结果表明:上层2-2煤开采时,覆岩破坏特征与单一煤层开采时相似;下层3-1煤开采时,由于煤层相对较厚,两煤层间的岩层破坏严重,裂隙发育,且引起2-2煤覆岩发生二次扰动破坏,裂隙进一步发育;两煤层间以及采区边界的岩层裂隙自修复程度较低,自修复难度较大。导水裂隙带高度随宽深比的增大总体呈降低趋势,随深厚比的增大总体呈上升趋势,并与实测数据进行对比验证。

Studying the feature of overlying rock failure and the height of water-conducting fracture zone after coal seam mining is the foundation for the source reduction design and differentiated surface ecological restoration. Taking the typical working face of Shendong Shigetai Mine as the engineering background,an independently developed simulation testing platform was used to study the characteristics of overlying rock failure and its self-healing after multi-seam coal mining. The relationship between height of water-conducting fracture zone and the width-to-depth ratio and depth-to-thickness ratio of the working face was revealed. A prediction formula of the height of water-conducting fracture zone was also proposed. The results showed that the overlying rock failure characteristics weresimilar to those of a single coal seam during the mining of 2-2 coal seam. During 3-1 coal seam mining,the rock layer between the two coal seams was severely damaged and the fractures were developed extensively due to the relatively thick coal seam. It caused secondary disturbance and damage in the overlying rock layers of the 2-2 coal seam,with further development of fractures. The degree of self-healing of rock fractures between two coal seams and at the boundary of the mining area was relatively low,making it difficult to self repair. The height of water-conducting fracture zone in Shendong Mining Area tended to decrease with the width-to-depth ratio,and it increased with the depth-to-thickness ratio,which had been verified using the measured data.